Torture is wrong because… The holding of prisoners of conscience is wrong because… The oppression of women is wrong because… If you finish these sentences with anything other than ...because it violates universal human rights, you leave yourself wide open to attack by your opponents.

Although I am sure that Britain is a happier country than Saudi Arabia and that a sensible person would rather live in France than Cuba, the case for basing societies on liberties is not a utilitarian one. Listen to the current debate on rights, however, and you will find that virtually everyone involved pretends that we can enjoy them without paying a price; that a cost-benefit analysis will always show gain without pain.

On the face of it, the Court of Appeal upheld universal human rights when it decided to release a summary of US intelligence that showed American interrogators had shackled Binyam Mohamed, a suspected supporter of the Taliban, and subjected him to sleep deprivation. But a closer examination shows that the judges did not say that Mohamed was entitled to evidence that supported his allegation that MI5 was complicit in his mistreatment, regardless of the consequences for the relationship between the British and US intelligence services.

Instead, they comforted themselves with the Pollyannaish notion that there could be no bad consequences for the espionage agencies. David Miliband warned them that intelligence sharing between the two countries would suffer if they ordered the publication of information given in confidence by an ally. The Master of the Rolls, Lord Neuberger, pooh-poohed his concerns. Because an American judge had already released details of the Mohamed case, he found it "impossible to believe that the US government would object to the publication" by the English courts.

No sooner had he ruled than a "deeply disappointed" Obama White House objected most forcibly. "As we warned, the court's judgment will complicate the confidentiality of our intelligence-­sharing relationship with the UK, and it will have to factor into our decision-making going forward."

Fiat justitia ruat caelum – "let justice come though the heavens fall" – but many will tolerate justice only if it leaves the heavens undisturbed. According to the Mohamed judgment, a man's right to obtain evidence that he has been tortured depends on whether the judges think that it may harm the intelligence services. If the Court of Appeal has got it wrong, and it seems to have got it very wrong, then the policy could change.

The judges are not alone in their desire for an easy life. Most of today's assumptions about human rights in wartime rest on the dangerous belief that they entail no risks. Writers on torture insist that it "does not work", as if the argument against torture depended on its efficacy, and as if the case for torture could be made if a torturer proved in an experiment on unwilling victims that it could be remarkably persuasive.

Jonathan Evans, the head of MI5, added a further complication when he said that the Mohamed ruling provided a propaganda victory for our enemies. And I am sure he was right. Press TV and the other propaganda organs of the Iranian and jihadi causes will not be balancing tales of Mohamed's torture with glowing descriptions of how kind Britain was to allow the Ethiopian to live here, even though he had lost his claim to be a refugee. If you want to be an accountant, you must take Evans's concern seriously, and put the effect that decisions in human rights cases have on boosting the enemy's morale in wartime into a profit-and-loss register.

But therein lies the problem. Most of the British do not behave as if they are at war. Every third-rate political pundit has ruled that we cannot say that we are in a "war on terror". Meanwhile, politicians will not allow us to say that we are in a "war against radical Islam" because they have to pretend that religion does not motivate religious extremists. Few argue, because although Jihadists have slaughtered tens of thousands, the dead are buried in Afghanistan, Iraq and Pakistan. The only British civilian casualties died in the 7/7 bombings, almost five years ago.

Only the atmosphere of phoney war can explain how Amnesty International, once the most principled defenders of human rights, has shown the truth of Robert Conquest's maxim that "the behaviour of any bureaucratic organisation can best be understood by assuming that it is controlled by a cabal of its enemies". All it had to do in the case of Guantánamo Bay was stick to the idea that suspects should not be held without trial and without the protections of the Geneva Convention. Instead, it collaborated with former Guantánamo inmate Moazzam Begg, whose Cageprisoners organisation promotes the supporters of ultra-reactionary ideals. More disgracefully, when Gita Sahgal, head of Amnesty's gender unit, and one of the most principled feminist writers I have read, complained that her employers were treating "Britain's most famous supporter of the Taliban" as a "human rights defender", Amnesty suspended the feminist and stuck by the Islamist.

Assuming that the far left has not taken control of Amnesty, and that may be a generous assumption, its managers must believe at some level that messianic religion is not a threat to the liberal values of feminism, anti-racism and freedom from tyranny they think they hold. To put it another way, Amnesty is living in the make-believe world of a phoney war, where it thinks that liberals are free to form alliances with defenders of clerical fascists who want to do everything in their power to suppress liberals, most notably liberal-minded Muslims.

I worry about what will happen when they realise that promoting human rights isn't a one-way bet, and that the Islamists they embrace aren't nice metrosexuals who support women's rights and want an end to bigotry. I hope that they and the judges will return to where they were before and remember that promoting human rights is a hard and often thankless task that has to be done regardless of the consequences. But there are no guarantees. They could equally become so disillusioned that they give up, and in a time of liberal betrayal that would be the greatest betrayal of all.